The present invention relates to a control apparatus for a machine, in particular for use in the control of an injection molding machine.
Nothing in the following discussion of the state of the art is to be construed as an admission of prior art.
The control apparatus of an injection molding machine is typically of modular construction, with various modules assuming different control tasks and providing the connection with particular controllable devices of the injection molding machine, such as, e.g., pressure sensor and motor drive. These modules are interconnected by a back plane bus and oftentimes constructed for insertion in a so-called “rack” having a back wall which has attached thereto a so-called bus board with a back plane bus. The connection between modules and back plane bus is predominantly implemented via plug contacts. Heretofore, a module provides a SPC (stored-program control) in which a safety logic of the injection molding machine is stored. In addition, the control apparatus includes a so-called wiring board for realizing the wiring including the safety circuitry of the machine and providing a voltage distribution for the control apparatus. The wiring board thus provides the voltage distribution with fuse protection, the safety circuitry including possible safety relays as well as further assemblies as well as a greatest possible portion of the wiring of the machine and its safety circuitry. A so-called process module which is securely mounted onto the wiring board has a base range for analog and digital control input and output connections to the injection molding machine. The connection between the control modules and the bus board, respectively, and the assemblies upon the wiring board is realized separately via individual cables.
Up to now, assembly of such a control has been very cumbersome because of the many separate components and thus also prone to failure. In particular the separate wiring of the individual units of the wiring board with the control modules lacked clearness and posed a risk factor. When the injection molding machine is upgraded and the number of controlling components is thereby increased, the existing control apparatus was faced with the problem to provide an adequate control operation. A further drawback resided in the necessity to individually wire each production line of injection molding machines.
It would therefore be desirable and advantageous to provide an improved control apparatus for a machine to obviate prior art shortcomings and to allow through standardization a reduction in costs and moreover is less prone to error while being flexible in use and as compact as possible.